"On the propagation of a pulse through a dispersive medium."
"Contrary to what is given in many textbooks, after a sufficiently long time a pulse transmitted through a dispersive medium with a significant quadratic term is proportional to the Fourier transform? of the original pulse shape.
By thinking backwards from a truncated transform, one sees that production of power pulses at a distance may be possible by multifrequency transmission of Fourier transform? patterns. Each frequency transmitted may be from a different transmitter and location, so long as the aggregate converges at the distant desired spot. By using scalar beams to so converge, one recovers all the transmission of energy without loss, and in a geometric pattern of one's choice. This seems to be the mechanism for the Tesla shield. [Jones, J.; American Journal of Physics. 42(1), Jan. 1974. p. 43-46.]